1. Field of the Invention
This disclosure is related to the field of insulation cutting machines. More specifically, the present disclosure relates to devices, methods and processes for cutting insulation such as cutting insulation for ductwork consisting of thick fiber on various types of backing including reflective aluminum backing.
2. Description of the Related Art
Thermal insulation is an important component in achieving thermal comfort for the occupants of building structures. Specifically, insulation reduces unwanted heat loss or gain, can decrease the energy demands of heating and cooling systems and can increase sound attenuation.
Insulation is often utilized in ductwork to increase the comfort, energy efficiency and sound attenuation of forced-air heating and cooling systems. In building structures with forced-air heating and cooling systems, ducts are used to distribute air throughout the structure. Stated differently, air ducts are the throughways through which treated air from heating or conditioning equipment in forced-air systems is distributed throughout the building structure.
Air ductwork is usually constructed out of thin metal sheets that, due to their physical construction and properties, easily conduct heat. Generally, air ducts lose heat in three main ways: first by conduction of heat through contact of the material with the surrounding air; second by radiation; and third by leaking through the cracks and seams of the air duct system. In fact, according to the United States Department of Energy, due to extreme winter and summer temperatures present in unconditioned spaces where ducts travel, about 10 to 30 percent of the energy used to heat and cool air is lost through conduction through duct surfaces.
It is well known that this energy loss in ductwork systems can be mitigated through the use of insulation—good duct insulation will improve the energy efficiency of insulated forced-air systems. When utilized, insulation has the ability to save money by increasing the efficiency of heating and cooling systems by as much as twenty (20) percent.
The insulation that is utilized for ductwork systems is generally comprised of materials used to reduce heat transfer by conduction, radiation or convection in varying combinations to achieve the desired outcome; i.e., thermal comfort with reduced energy consumption. One type of insulation commonly used in air ducts is thermal batting (batts) or blankets. This type of insulation is generally available in large, continuous rolls. Notably, compression or matting of the material which comprises the blanket impairs its functionality. Common materials utilized to create thermal blankets include, but are not limited to: rock and slag wool (usually made from rock (basalt, diabase) or iron ore); fiberglass (made from molten glass, usually with 20% to 30% recycled industrial waste and post-consumer content); high-density fiberglass; plastic fiber; polyester fiber; and elastomeric materials. Generally, thermal blankets comprised of elastomeric foam and plastic fiber have numerous beneficial thermal properties over insulation comprised of fiberglass. In addition, these types of insulation are not as abrasive as fiberglass-based thermal blankets. However, due to their high density and fibrous content, these forms of insulation are notoriously hard to cut and handle.
Often, many insulative thermal blankets further include a thermally reflective surface called a radiant barrier. This material is added to the thermal blanket to reduce the transfer of heat through radiation as well as conduction. When a radiant barrier, such as aluminum sheet or another commonly utilized reflective substance, is utilized it creates a reflective insulation product that is able to control conductive heat transfer, radiant heat transfer, and condensation all in one product.
While beneficial from a thermodynamic standpoint, this thermally reflective surface can add complexity to the cutting of the thermal blanket—it makes it harder to get a clean and precise cut. For example, new thermally beneficial insulative thermal blankets such as PolyArmor® by Ductmate (a polyester duct liner—fiberglass free—with a radiant layer backing) can be notoriously difficult to cut and manage.
Despite the fact that the use of insulation has become ubiquitous in the ductwork industry, the methodologies for cutting insulation for ductwork have remained old-school, outdated and rudimentary. A large majority of insulation is still cut manually and by hand using box cutters, utility knives, round knives and/or passive rotary blades (i.e., non-powered rotary blades or “pizza cutters”) with a guide for the respective outline of the size of insulation desired. In this conventional methodology, a worker rolls out the thermal blanket, places a cutting guide over the thermal blanket that corresponds with the desired shape of the thermal insulation to be cut, and utilizes a box cutter, passive rotary blade or other known non-powered blade mechanism to cut around the guide to cut out the desired shape from the thermal blanket. In this process, the cutting mechanism often fails to make a clean cut through the thermal blanket. Further, the radiant layer is also often improperly cut or torn in this procedure.
This conventional manual method for cutting insulation is problematic on a number of levels: it is high in cost, requires manual labor, is inefficient, ruins the product (as noted previously, it often chops the product off), and results in a very imprecise cut. In addition, as fiberglass is very abrasive, the thermal blanket can quickly wear down the blade of the cutting apparatus utilized, resulting in this equipment having to be changed often (and thus further adding to the cost of the procedure). In sum, the conventional method for manually cutting thermal blankets for rectangular air duct and fittings is a time and money waster. This is especially true now that, in many markets, thermal blanket insulation costs more than the sheet metal to which it is attached.
While some alternatives to manual insulation cutting have emerged in the market, these methodologies are still insufficient for a number of reasons. Water jet cutting, while providing precision and accuracy in cutting, still lacks the efficiency and speed required to utilize it as a cutting methodology on an automated assembly line. Further, water jet cutting still includes a manual component—the pieces, once cut, are removed from the thermal blanket by hand. This manual removal exposes the pieces to tearing, compression and other manual damage.
Another mechanized method of insulation cutting currently utilized in the art is the chop method. In this method a long knife blade is utilized in an assembly line in a guillotine-like fashion—when released it cuts the insulation blanket via a chopping methodology. Yet another newly-utilized method for cutting ductwork insulation is the swing blade method. Similar to the chop method, in this method a long knife blade is utilized on an assembly line. In this method, the serrated long knife blade is released and slices through the thermal insulation. Generally, in this method, the knife blade is affixed to two pivoting brackets that allow the knife to swing down while remaining parallel with the thermal insulation and chopping through in a swinging motion quite similar to the chopping methodology, but allowing for some side-to side cutting action.
Notably, both the chop and the swing blade methods are utilized on ductwork assembly lines. These assembly lines, as will be discussed further in this application, generally function as follows. Pieces of cut metal ductwork that correspond to particular sections of the ductwork structure to be assembled travel down a belt in the assembly line. In addition to the continuous stream of cut metal ductwork pieces, a continuous stream of thermal insulative blanket, which will be adhered to the precut metal ductwork, also travels down the assembly line. Generally, the thermal insulative blanket is adhered to the precut metal ductwork by glue or similar adhesive and nails (called pins) (or similar fastening methodology). This adhesion of the sheet metal and insulative blanket to each other generally occurs in a continuous manner.
This continuous stream of insulative blanket and precut sheet metal generally requires uninterrupted cutting of the thermal insulative blanket so that the merger and adhesion of the two pieces (sheet metal and insulation) will not be impermissibly altered. Thus, quick automated technologies, such as the chop and swing blade method, are utilized so that a cut can be accomplished without interrupting the continuous stream of component parts down the assembly line. That is, the flow is not stopped for the cutting action. Thus, the cutting action is generally very quick and is along all the points of cutting at once so that a straight, and not angled, cut is made. The problem with both of these automated technologies however is the motion is often not sufficient to cut through elastomeric thermal insulation blankets that are further comprised of a layer of radiant material because of the extra resistance it provides.
Accordingly, there is a need in the art for an insulation cutting mechanism that can be utilized in an automated production line that is able to properly cut-through all types of thermal insulation blankets (including elastomeric-based thermal blankets with a reflective layer) without damaging the insulation in the cutting process